Like described here: https://docs.godotengine.org/en/stable/tutorials/io/encrypting_save_games.html
The article isn't really about security, but format. Any of those file formats, you can then encrypt using Godot's open_encrypted with...() functions. Naturally, it makes some of them - like human-readable - files a lot less useful because they can now no longer be opened by a human unless they can decrypt it.
So overall, it does not change much - encrypt if you want encrypted files!
However, how to store passwords for encrypted files in a secure manner is a very different topic that would require a tutorial or course on its own that isn't really part of most game development purposes.
Sorry, I forgot to mention the section I was thinking about when suggesting encryption: "Preventing players from reading the saved data".
The section suggests to "use binary files" "to prevent players from reading the saved data, whether it’s to slow down cheating or data mining". Using a text-based format with encryption could be a convenient alternative to achieve the same goal.
Yes, I don't disagree, especially during development when you want to take a look at the data without having to re-write your save routine to use binary. But as I noted, keeping your files secure is a whole other topic that I just couldn't address in a single article.